1. Field of the Invention
The present disclosure relates to a pintle-swirl hybrid injection device.
2. Description of the Related Art
Referring to FIGS. 6 and 7, engines in launch vehicles with a conventional injection device such as rockets and so on generally include a housing 3 defining a combustion chamber 3a therein, and an injection device 100 installed at a center of the housing 3.
Referring to FIGS. 6 and 7, the injection device 100 includes a body 110 in a tubular shape, which is installed in the housing 3 with one side being exposed toward the combustion chamber 3a, and an injection tip 120 coupled with the end of the side of the body 110 exposed to the combustion chamber 3a. 
An oxidizer flow passage 110a is defined inside the body 110 to supply the oxidizer, and the oxidizer flow passage 110a is fluidly communicated with the combustion chamber 3a to inject the oxidizer to outside.
In the above example, the injection tip 120 is coupled with an one side end of the body 110 and determines an injection direction of the oxidizer injected to outside. That is, the oxidizer is injected from the body 110 by the injection tip 120 coupled with the one side end of the body 110, in a radial direction of the body 110 and in a diagonal fashion toward the combustion chamber 3a. 
Meanwhile, a fuel flow passage 100b is formed between the housing 3 and the injection device 100, through which the fuel is supplied toward the combustion chamber 3a. Specifically, the fuel flow passage 100b to supply the fuel is formed along an outer wall of the body 110 of the injection device 100 installed in the housing 3, and the fuel flow passage 100b is formed in a structure such that the fuel flowing therein is injected toward the combustion chamber 3a in the axial direction of the body 110.
Accordingly, the oxidizer injected from the body 110 toward the combustion chamber 3a in the radial direction of the body 110, and the fuel injected along the outer surface of the body 110 in the axial direction of the body 110 collide into each other, thus being sprayed and burnt into high-temperature and high-pressure gas.
However, by the conventional technologies, the high-temperature and high-pressure gas is formed in the radial direction of the body 110 and sprayed into the combustion chamber 3a. Accordingly, there occurs areas where the high-temperature and high-pressure gas re-circulates, i.e., at the front of the injection device 100 where the injection tip 120 is disposed, and in the radial direction of the body 110 which is exposed to the combustion chamber 3a. 
Accordingly, the high-temperature and high-pressure gas re-circulating at the front of the injection device 100 heats the externally-exposed outer wall of the injection tip 120 and damages the injection tip 120, and the high-temperature and high-pressure gas re-circulating at the front of the body 110 exposed to the combustion chamber 3a turns into highly-concentrated fuel state, thus hindering efficient combustion.
Meanwhile, to address the problems mentioned above, the conventional technologies have utilized the method of coating a heat-resistant material on the outer surface of the injection tip 120. However, the method can only temporarily protect the injection tip 120 from the high-temperature and high-pressure gas, but is not suitable for long period of use.